libstdc++: Check for multiple modifiers in chrono format string [PR110708]

The logic for handling modified chrono specs like %Ey was just
restarting the loop after each modifier, and not checking whether we'd
already seen a modifier.

libstdc++-v3/ChangeLog:

	PR libstdc++/110708
	* include/bits/chrono_io.h (__formatter_chrono::_M_parse): Only
	allow a single modifier.
	* testsuite/std/time/format.cc: Check multiple modifiers.

diff --git a/libstdc++-v3/include/bits/chrono_io.h b/libstdc++-v3/include/bits/chrono_io.h
index 87caa30b83ae03583db647809af3913abf3a3138..5f06a6d76b43b03bbaa0fb3bd6a81a4f9b15ba74 100644 (file)
--- a/libstdc++-v3/include/bits/chrono_io.h
+++ b/libstdc++-v3/include/bits/chrono_io.h
@@ -426,6 +426,11 @@ namespace __format
                  break;
                case 'O':
                case 'E':
+                 if (__mod) [[unlikely]]
+                   {
+                     __allowed_mods = _Mod_none;
+                     break;
+                   }
                  __mod = __c;
                  continue;
                default:

diff --git a/libstdc++-v3/testsuite/std/time/format.cc b/libstdc++-v3/testsuite/std/time/format.cc
index b05e5da1af85876036bd1bf3e54cbd48b1e89477..0dc45d58dcee74d0eb2491fd2b7ec91b09d2b8e0 100644 (file)
--- a/libstdc++-v3/testsuite/std/time/format.cc
+++ b/libstdc++-v3/testsuite/std/time/format.cc
@@ -68,6 +68,16 @@ test_bad_format_strings()
   // modifier not valid for conversion specifier
   VERIFY( not is_format_string_for("{:%Ea}", t) );
   VERIFY( not is_format_string_for("{:%Oa}", t) );
+
+  // more than one modifier (PR libstdc++/110708)
+  VERIFY( not is_format_string_for("{:%EEc}", t) );
+  VERIFY( not is_format_string_for("{:%EEEc}", t) );
+  VERIFY( not is_format_string_for("{:%OOd}", t) );
+  VERIFY( not is_format_string_for("{:%OOOd}", t) );
+  VERIFY( not is_format_string_for("{:%EEy}", t) );
+  VERIFY( not is_format_string_for("{:%OOy}", t) );
+  VERIFY( not is_format_string_for("{:%OEy}", t) );
+  VERIFY( not is_format_string_for("{:%EOy}", t) );
 }
 
 template<typename I>